Therapeutic Establishment for Gingival Hyperplasia and Scar Formation by Use of Collagen-Digestible Proteases

牙龈卟啉单胞菌和牙髓卟啉单胞菌分别是人类慢性牙周炎和根尖周炎的主要病原菌。它们结合了来自环境的二肽和三肽作为碳和能源。在本研究中，我们克隆了牙髓巴氏杆菌ATCC 35406的一个新的二肽基肽酶基因，命名为Dpp11。同源性搜索发现了牙龈假单胞菌的同源基因PGN0607，它被归类为真正的DPP7的同功体。DPP11用倒数第二个N-末端天冬氨酸和谷氨酸特异性地去除了寡肽中的二肽。Arg_&lt；670&gt；是一种在所有DPP11成员中完全保守的唯一氨基酸，而在所有真正的DPP7成员中，该残基被转化为甘氨酸。取代分析表明，Arg_&lt；670&gt；与底物的酸性残基相互作用。考虑到DPP11优先利用酸性氨基酸，确保在这些革兰氏阴性厌氧菌中有效地降解寡肽底物。为了研究脱落毒素A引起葡萄球菌性烫伤皮肤综合征的机制，我们在大肠杆菌中表达和纯化了脱落毒素A及其N端截短的衍生物(Δ38和Δ57)和失活的衍生物(Ser233Ala)。重组ETA(Wt)显示了Lle-MCA的多肽酶活性。这是除DSG1外，首次报道ETA具有多肽酶活性。如果ETa衍生物(wt和Δ38)具有肽酶活性，则ETA及其衍生物对新生小鼠有毒性作用，而不具有肽酶活性的ETA(Δ57和SerΔ233Ala)不会引起疾病。这一发现表明，ETA的多肽酶活性是毒素活性所必需的。

Porphyromonas gingivalis and Porphyromonas endodontalis, asaccharolytic black-pigmented anaerobes, are predominant pathogens of human chronic and periapical periodontitis, respectively. They incorporate di-and tri-peptides from the environment as carbon and energy sources. In the present study, we cloned a novel dipeptidyl peptidase(DPP) gene of P. endodontalis ATCC 35406, designated as DPP11. A homology search revealed the presence of a P. gingivalis orthologue, PGN0607, which has been categorized as an isoform of authentic DPP7. DPP11 specifically removed dipeptides from oligopeptides with the penultimate N-terminal Asp and Glu. Arg_<670> is a unique amino acid completely conserved in all DPP11 members, whilst this residue is converted to Gly in all authentic DPP7 members. Substitution analysis suggested that Arg_<670> interacts with an acidic residue of the substrate. Considered to preferentially utilize acidic amino acids, DPP11 ensures efficient degradation of oligopeptide substrates in these gram-negative anaerobic rods.In order to investigate the mechanism of Staphylococcal scalded skin syndrome(SSSS) caused by exfoliative toxin A(ETA), we expressed and purified ETA and its N-terminally truncated(Δ38 andΔ57) and inactive(Ser233Ala) derivatives in E. coli. Recombinant ETA(wt) showed the peptidase activity for LLE-MCA. This is the first report that ETA showed the peptidase activity other than Dsg1. ETA and its dirivatives exerted toxin activity to newborn mice, if ETA derivatives(wt andΔ38) possessed the peptidase activity, while ETAs with no peptidase activity(Δ57 and SerΔ233Ala) did not cause the disease. This finding indicated that the peptidase activity of ETA was indispensible for the toxin activity.